Heat exchanger system for ice making machines



June 6, 1961 E. J. KOCHER ETAL 2,986,903

HEAT EXCHANGER SYSTEM FOR ICE MAKING MACHINES Filed Feb. 9, 9

2,986,903 HEAT EXCHANGER SYSTEM FOR ICE MAKING MACHINES This invention relates to an improved heat exchanger system for ice freezers.

In prior art ice freezer systems which utilized an ac cumulator in conjunction with the freezer, oil which was entrained in the refrigerant came in contact with the heat transfer surface of the freezer. As the heat transfer rate of the freezer must be high, this fouling of the transfer surface resulted in lower overall capacity of the machine.

Accordingly, the present invention provides an improved heat exchanger system for ice making machines, in which system the oil containing refrigerant does not contact the freezer heat transfer surface. The invention contemplates the use of a heat exchanger with the accumulator, and also the use of a closed circuit of secondary refrigerant between the heat exchanger and freezer.

More specifically, the invention contemplates an arrangement, as above indicated, which employs a shell and tube heat exchanger having its shell side connected with the freezer heat transfer surface, and having its tube side connected to the accumulator. As a result, the refrigerant which is in contact with the freezer wall cannot be contaminated with oil, and consequently the heat transfer rate in the freezer is maintained at a high level. Although the tube side of the heat exchanger may be fouled with oil, the effect is not as critical as if the freezer surface were fouled, because the transfer rate in the exchanger is considerably lower than in the freezer. Good overall capacity is thus maintained even under fouled conditions.

These and other objects and advantages will appear hereinafter as this disclosure progresses, reference being had to the accompanying drawings, in which,

FIGURE 1 is an elevational view of a heat exchanger system for an ice freezer which is constructed according to the present invention; and

FIGURE 2 is a cross-sectional view taken on line 2-2 of FIGURE 1.

Referring in greater detail to the drawings, the ice freezer F comprises a cylinder having double walls 3 and 4 between which is formed an annular refrigerant space 5. A rotor 6, carrying the water distributing pipes 7 and ice removing knives 8, is mounted inside the freezer and is connected by a flexible coupling 9 to its motor reducer unit 10. As the rotor turns, water is sprayed on the inner surface of wall 3 where it freezes into ice I almost instantly, and is then scraped off in a crystal form by the knives for subsequent delivery through the spout S.

A shell and tube type heat exchanger E is provided which contains a series of horizontally disposed tubes 11, the interior of which are in communication with the accumulator A by means of the liquid inlet conduit 13 and the vapor outlet conduit 12. Conduit 13 is connected intermediate the height of the liquid leg 14 which communicates at its upper end with the accumulator body 15.

The shell side of the heat exchanger is in refrigerant delivering communication with the annular space of the freezer by means of the liquid refrigerant inlet conduit 16, the manifold pipe 17 and the axially spaced branch conduits 18. The vapor refrigerant outlet conduits 19 "ice connect the uppermost side of chamber 5 with the exchanger shell 20 at locations intermediate the height of the latter. In this manner, a closed circuit of secondary refrigerant is formed between the freezer and exchanger, and the captive charge of refrigerant is circulated therethrough.

End bafile plates 22 and 23 are provided in the exchanger so that the flow of liquid refrigerant L is through the leg 14, the lower tubes as indicated by the arrows, back through the upper tubes as indicated, and then as a vapor through conduit 12.

An oil drain valve 25 is provided at the lower end of the leg 14.

The accumulator A is shown as a liquid ammonia type and includes a suction line 26 through which vapor is conducted to the conventional compressor (not shown). This accumulator also includes a liquid refrigerant inlet 27 and a low pressure float control valve 28.

In operation, the captive charge of refrigerant which is contained in the shell side of the heat exchanger and the freezer boils as it receives heat from the freezing water. The vapors formed pass through the upper connections 19 and into the heat exchanger where they condense on the cold tubes that are refrigerated by the main system. The condensate so formed then flows by gravity through the lower connections 16, 17 and 1 8 back into the freezer. This secondary refrigerant which contacts the freezer Wall cannot be contaminated with oil and the heat transfer rate is maintained at a high level. Although the tube side of the exchanger may be fouled with oil, the exchangers heat transfer rate is not as great as that of the freezers and therefore not as critical, thus overall capacity is maintained and the use of a larger or oversize freezer for any particular installation is not required.

Various modes of carrying out the invention are contemplated as being within the scope of the following claim particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

We claim:

In combination, an ice freezer having an annular refrigerant space through which secondary volatile refrigerant is adapted to pass, means for removing ice accumulations from one surface of said freezer, an accumulator for primary volatile refrigerant located above said freezer, and a heat exchanger comprising a horizontally disposed cylindrical shell having a series of horizontal tubes therein and located intermediate said accumulator and said freezer, said tubes comprising a tube side of the exchanger through which only said primary volatile refrigerant is circulated directly from and to said accumulator, said exchanger also having a shell side in direct communication with a lower portion of said freezer space for delivering only volatile liquid refrigerant thereto, said shell side also in direct communication with an upper portion of said space for receiving only vapor refrigerant therefrom, said shell side thereby forming a closed circuit with said space through which said secondary volatile refrigerant is circulated only by evaporation.

References Cited in the file of this patent UNITED STATES PATENTS 2,018,462 Morrow Oct. 22, 1935 2,596,195 Arbuckle May 13, 1952 2,778,200 Gaugler Jan. 22, 1957 FOREIGN PATENTS 558,944 Germany Sept. 13, 1932 

